Distributions of morphological characters and more

[Nick Gardner <nick.gardner@gmail.com>]

Has anyone else noticed there is a tendency in many cladistic analyses
(especially ornithischians) to focus on cranial characters, while
paying little (if any) attention to those of the postcrania? I realize
the skull represents a cornucopia of characters, but surely, I've
noted numerous postcranial characters have been published, but it is
rare for them all to ever come together in a single published analysis
so far, and I've often seen ones that have not yet even been run in a
cladistic analysis. It is somewhat true that ornithischian
phylogenetics are behind that of theropod phylogenetics, but it just
seems rare to find any major examination of the postcranial skeleton
for characters. Is this an artifact of limited material or research
being done, or does it truly represent a lack of characters from the
postcrania? I'm inclined to believe the former.

I did some numbers from Sereno's "The Evolution of Dinosaurs"
'analysis' using all the datasets, and approx. 56% of the characters
used were postcranial (approx. 13% axial, approx. 19% forelimb,
approx. 23% hindlimb) and approx. 41% were cranial, while the rest of
the characters didn't really fit in either category (i.e. body size)
or concerned dermal structures (osteoderms, feathers, etc.).

Additionally, I've the following character in my analysis:
Premaxillary tooth number: 0- four; 1- two; 2- three; 3- five; 4- six;
5- seven; 6- zero.

Should the sixth character state (zero premaxillary teeth) be
separated as "premaxillary teeth: 0-present; 1- absent" or is it fine
as a state within a character counting the number of premaxillary
teeth? I seldom see it included, but I note that Sereno uses it within
his own analysis in this fashion (see character 4.49:2 and 5.31:2 for
example), though I realize he is not necessarily an esteeming role
model to follow for cladistic analysis. >>

Also, the supratemporal and infratemporal "bars" referred to
separately by Sereno and You, what exactly are they? Is the
supratemporal "bar" the postorbital-squamosal contact separating the
laterotemporal fenestra and the supratemporal fenestra, and the
infratemporal "bar" the jugal-quadratojugal contact that forms the
ventral margin of the laterotemporal fenestra?

Additionally, You uses palatal characters describing "choanae" in his
cladistic analysis, regretably, I've not been able to find out what
these are. Can someone please point me to a figure or paper that
adequately describes what part of the palate these are?

And finally, has there been any published critique of the
"compartmentalization" technique employed separately by Sereno,
Vermeij, and Carpenter? I am already aware of its flaws, but merely
seek out if there has been any published works against it. Thank you.

Nick Gardner